Controlling mechanism for motors.



c. R. PRATT. GOI TTROLLING MECHANISM FOR MOTORS.

APPLICATION FILED AUG. 7, 1908. 1,048,999, Patented Dec.31,1912.

3 SHEETSSHEET 1.

IQ-H51 1 as a c o G. R. PRATT.

CONTROLLING MECHANISM FOR MOTORS.

' APPLICATION rum) AUG. 7, 1908.

Patented Dec. 31, 1912.

3 SHEETSSHEET 2.

QW tmwo 5 51/ 7 APPLICATION FILED AUG. 7, 1908.

Patented Dec. 31, 1912.

3 SHEETSSHEET 3.

SUM-e11 Valuer; 77; 71/.

UNITED STATES PATENT oFFroE.

CHARLES R. PRATT, OF MQNTCLAIB, NEW JERSEY.

CONTROLLING MECHANISM F618, MOTORS.

Specification of Letters Patent.

To all whom it may concern:

Be it known that I, CHARLES R. PRATT, a citizen of .the United States,residing at Montclair, in the county of Essex and State of New Jersey,have invented a new and useful Improvement in Controllin Mechanism forMotors, of which theto lowing is a specification. I

My invention relates to mechanism for regulating and controlling thespeed of prime movers, such as steam engines, steam turbines, electricmotors, hydraulic motors, etc.

One of the objects provision of means for automatically regulating andmaintaining a uniform speed of a motor, regardless of the load.

Another object of the invention is to provide, incombination with amotor and regulating mechanism therefor, automatic means for positivelyoperating said mechanism when the motor varies from a predetermined ornormal speed to effect a return of the motor to normal s eed.

A further object 0 theinvention is the provision, in combination with amain or power motor and a controlling pilot motor adapted to. run insynchronism, of controlling mechanism for the main motor, and means forefiectmg a positive operatlon of said mechanismv when the relative speedof the motors is varied to effect alreturn to synchronism.

A still further object of the invention is to provide, in combinationwith a motor, improved controlling means for securing any desired speedof the motor within wide limits. 7

Other objects of the invention will appear hereinafter, the novelcombinations of elements being set forth in the appended claims.Referring to the accompanying drawings,

Figure 1 is an elevation view, partly d1agrammatic, showing an elevatorsystem to which my invention is applied; Fig. 2 is a sectional elevationon a larger scale of the planetary gearing located between the main andpilot motors, and the main motor controller adapted to be operated bysaid gearing; Fig. 3 is a view showing the main motor brake andbrake-operatingmechanism; Figs. 4; and 5 are respectively a-front and aside elevation showing certammodifications of the mechanism shown inFig. 2; and Fig. 6 is ,a diagrammatic View of electrical cirof theinvention is the- 12 are pivoted at 11 cuits andcontrollingmechanismwhich may be used in' connection with the elevator system shownin Figs. 1 to 3.

The invention is adapted to have a wide application in the regulationand control of the motors are out of synchronism to effect an increaseor decrease in the speed of the main motor to bring it into synchronismwith the pilot motor.

In order to show a practical application of the invention and to clearlyset forth its principles and methods of operation, I have illustrated inFigs. 1 to 3 an elevator system embodying one form of the invention. Ashere shown, an electric motor M is Patented Dec.31,1912. Applicationfiled August 7, 1908. Serial No. 447,359. 1

mounted on a bed-plate 8 secured to the I-beams 10 at the top of theelevator shaft. The elevator car C is suspended by cables 2 connected atone end to the car and extending upwardly over the drive sheave 3 on themotor shaft 4, down and around the idler sheave 5, upover the drivesheave 3 again, and down to the counterweight W to which the oppositeends are secured.

A brake pulley 6 keyed to the shaft 4 is conveniently located betweenthe motor and the drive sheave.-

and 12 to brackets 13 secured to or'formed on the body of the brakemagnet 1 1. A lever-15 is pivoted at 1 6 to the upper end ofthe brakelever 12. The lower end of the lever 15 is pivotally connected to a rod17 extending through the brake levers and provided at its free end withan adjustable stop or head 18. A brake-applying spring 19 surrounds therod 17 and bears at its opposite ends against the head 18 and the brakelever 11. The brake levers are adapted to be operated to lift the brakeshoes by the rods 20 connected at their The brake levers -11 and innerends to the cores of the. brake magnet.

These rods extend through openings in the.

lower ends of the brake levers, and are provided with nuts 21 foradjusting the positions of the magnet cores. When the brake magnet isenergized, its cores are drawn inward and lift the brake shoes from thebrake pulley against the tension of the spring 19.-

A buffer 19 of soft rubber or other elastic material may be mounted onthe rod 17 between the brake lever 11 and a washer 18' adjustably heldin position by a nut The washer 18" is preferably spacedia shortdistance from the elastic buffer, so that the latter will only becompressed during the final 1 portionof the movement of the brake lever.

If the spring 19 should break or become in-' operative, the nut 20' canbe set up toward the brake shoe 11 so that the rod 17 can operatethrough the elastic buffer to apply the 15 brake, the elastic bufferproviding for a yielding pressure of the brake shoes.

Mounted on the frame of the motor M is a casing 22 containing planetarygearing forming a connection between the main or 2 power motor M and asmall auxiliary or pilot motor P. J ournaled in bearings in the frame 22is a shaft 23, to one end of which is secured a sprocket wheel 24connected by a sprocket chain 25 to a sprocket wheel 26 25 secured tothe motor shaft 4. Keyed to the "loose on the shaft 23 and carryingbevel pinions 30 journaled on the radial arms of the spider and eachmeshing with the gears' 27 and 28. The spider 29 also carries an annularspur gear wheel or ring 31 located out- 5 side of the pinions 30 andmeshing with a gear wheel 32 secured to a shaft 33 journaled in bearings34. A pinion 35, fixed to the shaft 33, meshes with a gear wheel 36Journaled'on a sleeve 37 which also forms a bearing for the shaft 23.The gear wheel 36 carries a switch arm 9 provided with electricalcontacts a, b, 0, each in sliding engagement with and bridging twoarc-shaped contacts on the stationary disk 38 of the automaticcontroller K. The shaft 39 of the plot motor P 1s provided with a worm40 which meshes with a worm wheel 41 secured to or formed integral withthe gear Wheel 28. The lever 15 on the upper end of the brake 5o lever12 is connected by a link 42 to a crank arm 43 on a'rock-shaft 44journaled in the upper part of the casing 22. A switch arm 45 secured tothe shaft 44 carries a roller 46 located in the path of movement of acam 47 secured to or formed integral with the gear ring 31 The switcharm normally engages switch contacts 46'. A spring-pressed catch 48bears against'the end of the switch arm,

. and is formed with a shoulder 49 adaptedto move the car. This effectsa supply of cur-' rent to the pilot motor P through circuits presentlyto be described, so that said motor.

is started and runs at a speed depending on the extent of movement ofthe switch lever 50. Current is also supplied to the brake magnet 14 tolift the brakes, and to the main motor M to start it and run it at slowspeed.

The pilot motor operates through the worm and worm'wheel to rotate thegear wheel 28 in one direction, and the main motor M operates throughthe sprocket chain and gears to rotate the gear wheel 27 in the oppositedirection. The rotation of the gear wheels 27 and 28 rotates the pinions30 about their axes, and as the gear wheel 28 operatedby the pilot motorrotates faster than the gear wheel 27, the spider 29 is rotated on theshaft 23. This operates through the gears 31, 32, 35 and 36 to rotatethe switch arm 9 and move the contacts a, b, 0' over the stationarycontacts of the controller-K.' The movement of the arm 9 causesanincrease in the speed of the motor M by effecting a weakening of themotor field and a decrease in the resistance in the armature circuit.This increase in speed is in proportion to or varies with the extent ofmovement of the arm 9, and the motor continues to accelerate until thegear 27 is running at the same speed as the gear 28, when the arm 9 isbrought to rest in position to maintain the motor at said speed. Anyvariation in the speed of the main motor, due to an'increase or decreasein the load, orother causes, will cause the arm 9 to move in a directionto bring the motor back to normal speed. If the" car switch is moved soas to impart a different speed to the pilot motor, the speed of, the

main motor will be correspondingly changed, the differential gearingalways moving the controller arm 9 into position to bring the motorsinto. synchronism.

The arm 9 is driven by two separate and independent forces, 71. e., bythe controlling motor P-always tending 'to drive it away from the stopposition at a speed proportional to the speed of the motor P, and by thehoisting motor M normally driving it toward the stop position at aspeed-proportional to the speed of the motor M. Whenever the two motorsrevolve in opposite directions at the fixed relative speed at which theyare in synchronism,the arm 9 rema ns stationary. When the motor Mexceeds said explanation. Assuming the parts to be fixed speed relativeto the pilot motor,'..it moves the arm 9 to close circuits which retardits speed, and whenthe motor falls below said speed it moves the arm 9to close circuits which accelerate its speed.- If, therefore, the limitsof speed of the pilot motor co engage beneath the switch arm and preventitsreturn after said arm has been lifted by the cam 47. 9 4

The operation of the mechanism above de- 's cribed' will be understoodfrom the followspur gear wheel 24 is formed integral with the bevel gear27 and meshes with a spur pinion 26 on a shaft 27, which may beconnected directly or through anycsuitable train of gearing to the mainmotor. The annular gear 31 meshes with the gear pinion 32 on the shaft33, which latter may be connected to operate a cont-roller for the mainmotor. The'form of controller will of course depend to a large extent onthe kindof motor to be controlled, If the main motor is a directcurrent/electric motorgth'e ,controller may be the same as that shown inFig. 6, or any other desired form of controller adapted to control adirect current motor. If the main motoris a steam engine, the shaft 33may be connected to a slide valve or. any other form of mechanismusually operated by a centrifugal speed governor to control the speedof'the engine. Various other types of prime movers or power motors andcontrolling mechanism therefor may be used in connection with myinvention. The type of pilot motor used may also be widely varied tosuit varying conditions found in practice.

In Fig. 6 are shown the electrical circuits and controlling mechanismforming a part of my invention as appliedto an elevator system. Thismechanism comprises a manual switch or controller '5 which may belocated in the elevator car, an automatic controller K, reversingswitches R, It for the armature circults of the main motor, startingresistance X, X for the main motor, relay magnets j, k, Z,'m controllingthe resistance X, X, shunt field winding 53' and brake magnet coil-51for the main motor, brake magnet coil 52 for the pilot motor, magnet 62controlling a circuit; for the main brake magnet, magnets e and fcontrolling the circuits of the reversing switches, and relay magnets gand 72. The manual-controller S comprises the lever 50 carrying contacts54, 55, 56, 57 and 58, each adapted to bridge a pair of stationaryarcshaped contacts when the lever 50 is moved to the right orleft fromthe central position. The arm 9 of the controller K carries threeinsulated contacts cab and 0, each adapted to bridge various sets ofcontacts as the arm 9 is rotated.

With the parts in the position shown, a local or dynamic brake circuitthrough the main motor armature 7 may be traced from the brush 55through the conductor 56,-sta- 'tionary contact 57, sliding contact I),stationary contact 58, conductor 59, contact 60 of the reversing switchR, conductor'61,

contact 62, and conductor-63, to the 0 posite brush 64 of the armature.Current 1s supplied from the positive'and' negative mains,

B .designated by and The field coil 69 of the pilot motor receivescurrent at all times through a circuit which may be traced from thepositive main through conductor 70, contacts 67, 57, 71, conductor 72,field coil 69, and to the negative main. When the switch lever 50 ismoved, for example to the right, a circuit is established through thepilot mot-or armature, which may be traced through the conductor 70,contacts 66, conductor 73, coils of the magnet e, brake magnet coil 52for the pilot motor, pilot motor armature 1, magnet cl, contacts 65, andconductor 74: t0 the negative main. The magnet cl operates tolift itscore and close the switch 75, establishing a circuit through theconductor 76, switch 75, conductor 77, main brake magnet coil 51,-switch lever 45, and conductor 78 to the negative main. A circuit isalsoestablished through the magnet coil of the rev'ersin switch R by way ofconductor 70, contact 9', contacts 79,'convductor 80, switch 81,conductor 82, and magnet coil 83 of the reversing switch R. The

reversing switch R operates toopen the dynamic circuit through the mainmotor armature and establish-a line circuit through said armature asfollows,from the positive main through conductor 85, contacts 86', 86,conductor 87, starting resistance X, brush 64, armature .7, brush 55,conductor 88, contacts 89, 89', and conductor 90 to the negative main..A circuit is alsov closed through the field coil 53 ofthe main motor,which may be traced from the positive main through the conductor 91,contacts 92, a and 93, conductor 94, field coil 53, conductors 95 and 90to the negative main. As a result ofthese circuits,-thebrake magnet-sare energized and both the motors receive current through theirarmatures and field windings; the pilot motor I is operated at a speeddepending upon the distance the lever 5O hasbeen moved; and the-mainmotor will. run at slow speed in a direction to lift the car, with theresistance X in the arma- .ture circuit and a strong magnetic fieldi.

The arm 9 will be rotated in a counterclockwise direction by means ofthe differential gearing shown in Fig. 2. As .the arm moves from itscentral position, the sectional resistance 95 will be graduallyintroduced into the circuit of the field winding 53. thereby weakeningthe field and permitting the main motor to accelerate. If the arm 9continues its movement far enough, the contact 5 will bridge thecontacts97 speed of and 99 and thereby establish a circuit through the magnet ofrelay is. This circuit is from the positive main, through the conductor100, contacts 99, b, 97 conductor 101,

magnet 7c, conductor 102 to the negative main. The magnet k lifts itscore and closes the switch 103, thereby short-circuiting the section104: of the resistance X and per mitting a further increase in the speedof the main motor. When the contact?) reaches the contact 98, a circuitis closed through the conductor 100, contacts 99, b, 98, conductor 105,relay magnet j, and conductor 102 to the negative main. The magnet joperates to close the switch 107, and thereby shortcircuit the remainingsection 106 of the resistance X and permit the main motor to approachits normal full speed. When the the main motor has been brought intosynchronism with the pilot motor, the arm 9 will come to rest. Thisposition will .depend largely upon the load on the main 1 field of itsmagnet e.

tact strip 110 of motor. It will also depend upon the position of thelever 50. As the latter is moved to the right the resistance 106 willgradually be introduced into the circuit of the field coil 69, therebyweakening the field of the pilot motor and permitting its speed toincrease. This will result in a further move ment of the arm 9 to theright, so that the main motor may accelerate'to correspond with theincreased speed of the pilot motor.

WVhen the contact 0 engages the cont-acts 90, a circuit is establishedthrough the relay magnet 71 100, contacts 96 and 0, conductor 107,wind.-

negative main. The core of the magnet 72; carries three contact strips108, 109 and 110, adapted to bridge three sets of stationary contacts,the inner one. of each of which is connected to the conductor 111extending to the positive main. Then the magnet h operates, the uppercontact 108 establishes a clrcuit by way of conductor 111, contact 108,and conductor 112 to the main brake coil 51, and from the brake coil toswitch 45, and conductor 78 to the negative main. The second contactstrip 109 establishes'a circuit from the positive main'through saidcontact strip and conductor113 to the magnet f, and from thence to thenegative main. The magnet f is therefore excited to lift its core andopen the switches 81 and 114, bring: ing the armature 115 within themagnetic This latter magnet is not strong enough to lift its armature115, but after the magnet f has operated it acts as a holding magnet toretain the switches 81 and 114: open as long as the pilot motor isreceiving current. The lower conthe relay magnet it closes a circuit byway ofthe conductor-116 to the magnet coil 83 of the reversing switch R.

This circuit may be traced from the positive main through the conductorduction in speed The result, therefore, of the operationof the relaymagnet h is to maintain a circuit reversing switch nets d, e and f andthe manual switch as long as the contact 0 of the automatic controllerremains on the contacts 96, and also to effect the operation of themagnets e and f. The purpose of the magnets a and f, and the switch 81controlled thereby, is to insure the opening of the line circuit to thearmature 7 'and the closing of the dynamic brake circuit as soon as thecontact 0 has moved off the contacts 96, and to maintain the dynamicbrake circuit as long as the pilot motor receives current. I

To make clear the operation in stopping the main motor, we will assumethat while it is running at normal speed the switch lever 50 is thrownquickly back to central position. This will cut off the supply ofcurrent to the pilot motor and its brake coil, so that said motor willbe brought quickly to rest. reversing switch magnet or the main brakecoil which still receive current byi way of the circuits controlled bythe relay magnet h. As soon as the speed of the pilot motor is. reduced,the arm 9 begins to move back toward central position, graduallyintroducing the cuit, and also strengthening the shunt field togradually reduce the speed of the motor until. the contact 0 runs offthe contacts 96 and deenergizes the relay magnet It. By this timevthemain motor is running at slow speed. The operation of the magnet it cutsoff thesupply of current from the main brake coil and the reversingswitch magnet so that the magnetic line circuit to the'armature 7opened, and the dynamic circuit closed, bringing the motor quickly torest. If the switch lever 50 is moved part way back, only not far enoughto open the circuit to the pilot motor. the circuit for the magnet 71,will be opened and the reversing. switch will be operated the same aswhen the lever 50 was thrown to central positionas above explained, butthe main brake coil will still receive current by way of the switch andthe rewill be more gradual. When the dynamic circuit through thearmature 7 is first closed in slowing down the motor, it includes theresistance 120, which latter is gradually approaches its centralposition. Instead of having the sections of the resistance 120 connecteddirectly to the contacts on the controller, relay magnets similar to themag nets j and itv may be used to control such resistance. a I i Inslowing down the main motor when the load is suflicient to run it as adynamo, the dynamic circuit with the variable re- This does not directlyaifectthe resistance X into the armature cir-.

brake is applied, the

, through the main brake coil and through the independently of themagout out as the contact I) able the operator to maintain full control,

7 even when the speed is quite ,slow. In

other words, by varying the position of the manual switch lever, the arm9 may be moved to introduce'more or less. of the re sistance 120 and 95,and thereby secure any desired degree of dynamic braking action, so thata very slow speed may be maintained.

During the normal operation, the arm 9 is never carried beyond thecontacts 98, 99-

and 96, as the main motor will synchronize with the highest normal speedof the pilot motor before the arm 9 has been carried'beyond suchcontacts. If, however, while the motor is loaded, the current supplyshould suddenly be cut off, as, for example, by the blowing of a fuse,the load would cause the main motor to reverse, and thus drive the arm 9rapidly upward beyond said contacts. This would have substantially thesame effect as moving said arm toward central'position;

' that is, the contact a would be moved off the contacts 96, therebyopening the circuit 1 through the relay magnet h WhlCh would in turndrop its cont-acts 108, 1 09 and 110,

- however, the trouble was in some portion of' thereby effecting theopening of the line circuit to the armature 7 and the closing of thedynamic brake circuit. This latter circuit would at first include theresistance 121 which would gradually be cut out as the contact a movedupward until the armature 7 was practically short-circuited, therebyeffecting a powerful dynamic braking action to bring the motor equipmentto rest. If,

the dynamic circuit, so that said circuit remained open, the arm 9 mightbe carried around until the cam 47 (Figs. .2 and 3) engaged the roller46 on the switch arm and. lifted the latter. The arm 45 operates throughthe arm 43, link 42 and lever 15 to positively apply the brake. Theoperation of the arm 45 also opens the circuit of the brake magnet atthe contacts 46'. The

combined operation of the'two brake-applyin devices is thereforeobtained, which e ects a powerful action of the main brake. To move thecar' downward, the switch lever 50 is moved to the left to suppl currentto the pilot motor armature m t e reverse direction. Current is alsosupplied to the reversing switch R by we of conductors 70, 130, andswitch 114. he reversin switch R operates to close a circuit throng thearmature 7 in the opposite direction,

and including the resistance X. Both the motors and the controller arm 9will there'- fore be operated in the opposite direction. The controllerK is substantially symmetrical with respect to a vertical axis, and thecircuit connections from the left-hand side are similar to those alreadydescribed, so

that the operation of the controller during 41, the latter will} belocked stationary; or

the arrangement may be such that although the main motor could drive theworm 40', there would be considerable friction to overcome between theworm wheel and the worm. This is of advantage, for-instance, where anemergency brake is to beoperated with considerable power. In such eventthe main motor exerts considerable power to apply the brake through thecam 47, and if the worm and worm wheel are low pitch they cannot bedriven, and therefore act as a fulcrum for the main motor to act againstin appl ing the brake. This action may even ta e place during the.normal operation of the speed control. The pilot motor is intended tooperate only the speed control, and when the main m0- tor tends toexceed its synchronous speed, the worm'gear acts as a fulcrum for theower of the main motor to react on when it drives the differentialgearing to operate the control.

By arranging the worm gearing in this manner, a comparatively smallmotor can be used as the pilot or auxiliary motor. For example, in someelevator installations a H. P. auxiliary motor may be used in connectionwith alOO H. I. main motor,

or 2; H. P. auxiliary motor for the largest power units.

I wish not to be limited to the precise constructions herein shown, asvarious.

changes in the details of construction and arrangement of parts might bemade by those skilledinthe, art without departing from the spirit andscope of the invention.

What I claim is 1. The combination with a plurality of motors, ofdifferential gearin the'rebet-ween, a brake, and means operated ysaid'gearing to apply the brake.

2. The combination with a plurality of motors, of planetary gearingtherebetween, a brake, and mechanical means associated with said gearingfor operating the brake.

3. The combination with a plurality of motors, of means for maintaininga predetermined relative speed of the motors, a brake, and mechanismdependent on a variation in the relative speed of the motors foroperating the brake.

4. The combination with a plurality of motors, of a controlling devicefor one of the motors, mechanism for operating the controlling devicewhen the relative speed of the motors varies from a predetermined-between the motors, a

ratio, a brake, and mechanism for automatically operating the brake whenthe con.- troller has been operated beyond a predetermined point.

5. The combination with a main motor and a pilot motor, of differentialgearing speed controller, a

brake, and mechanical connections between the differential gearing andthe brake and 7. The. combination with an electric motor, of an'electro-magnetic reversing switch therefor, a pilot motor, a manualcontrolling device operable to establish circuits for the pilot motorand the ma net coil of the reversing switch and thereby effect theoperation of the motors, an automatic controlling device for saidelectric motor, 'and means for operating said device and therebyaccelerating said electric motor to a predetermined speed. i

8. The combination with an electric power motor, of a pilot motor, anelectro-ma etic reversing switch for the circuits 0 the power motor, amanual controller operable gearing of comparatively low 'nected to tosupply current to the pilot motor and close a circuit for the magnetwinding of the reversing switch, means operable when the power motorreaches a predetermined speed to establish. a second circuit to saidmagnet winding and also effect an opening of the first-named circuit,and means for holding said first-named circuit open while the pilotmotor is running.

9. The combination with a power motor,

of an electro-magnetic brake therefor, a pilot motor, a manual deviceoperable to effect the establishing of circuits for the pilot motor, themain motor, and the magnet coil of said brake, and means forautomatically establishing a by-pass circuit to said brake magnet whenthe power motor attains a certain speed.

10. motor,

The combination with a main electric of an auxiliary electric motor,worm pitch consaid auxiliary motor, differential gearing interposed ingand the main for the main motor, the difl'erential gearing motor, brakeapparatus and means operated by for powerfully aplat between said Wormgearplying the brake against the Worm gearing as a fulcrum.

In testimony whereof, I have signed my name to this specification in thepresence 0 two subscribing witnesses.

' CHAS. R. PRATT.

Witnesses: v

a CHAS. M; NISSEN,

WALTE C. STRANG.

